In general, the field is light-emitting devices of a discharge nature. More particularly, it is envelopes for lamps, the envelopes comprising two members hermetically sealed together with one member having an optical element formed within its surface.
Generally, there are two distinct types of lighting applications. In one, direction of the light is relatively unimportant. In the other, light must be directed in a particular manner subsequent to its generation. The present invention, while suitable for either application, is particularly well suited for the latter where light direction is important.
An example of the latter category is automotive lighting. After light is generated by a lamp, it must be focused/dispersed according to somewhat exacting standards. The requirements for light-directed lamps, such as headlights, sidemarkers, tail lights, brake lights, directionals, hazards, CHMSLs (center high-mounted stop lights), differ. However, they all share the characteristic that their light needs to be directed in some specific manner.
Heretofore, these lights have been constructed of a lamp element (for generating light) and a lens and/or reflecting element (for directing the light). Lamp elements generally fall into three categories: light-emitting diode (LED), incandescent and discharge.
Discharge lamps are generally characterized as having a sealed envelope filled with a gas, the atoms/ions of which, when properly excited, give off light. Lens elements may be categorized as refractive, fresnel, or Total Internal Reflection (TIR). There are also additional elements, such as various reflective surfaces.
An optimum lamp/lens configuration has long been sought by lighting designers. In particular, the automotive market has long desired to incorporate as much light directing capability into the light source (lamp) as possible. This desire has been hampered by the nature of most glass, lamp envelopes
One area of recent interest is that of neon lighting for automotive tail lights. For a neon light source to be effective as an automotive rear light, the light output needs to be directed efficiently at the SAE (Society of Automotive Engineers) target area. This area is +/xe2x88x9210xc2x0 from horizontal and +/xe2x88x9220xc2x0 from vertical. Minimizing stray light in the non-SAE zone allows the lamp to operate with the greatest energy efficiency and the least electromagnetic interference (EMI).
The traditional approach to accomplish this has been to use a reflector element in combination with a separate, plastic lens having optical elements that focus the light. These optical elements are typically refractive. They are limited in their ability to gather light, and will always require some measurable focal length. The latter, of course, adds depth to the total lamp assembly.
Therefore, there exists a great need for a lamp having an envelope which can integrate optical elements into the envelope itself. Also, the need exists for a lamp having an envelope which can integrate optical elements into a configuration that does not emit light as a point source. It is an object of the present invention to meet these needs.
It is a further object of the invention to provide a discharge lamp which has the ability to direct light in a preselected pattern or direction through an integrated lens.
It is yet another object of the invention to provide a method for manufacturing a laminated envelope for a discharge lamp which includes a lens element formed in the lamp envelope.
It is an additional object of the invention to provide a combination discharge lamp envelope and TIR lens.
It is another object of the invention to provide a laminated, internally channeled, discharge lamp envelope with integrated optics in direct juxtaposition to the channel.
The invention resides in part then in a lamp envelope for a light emitting device comprising a first and a second glass member, each member having an inner surface, the first member having a continuous channel that opens on its inner surface, the second member having an integral, optical element formed in at least one surface, the continuous channel and the integral, optical element being aligned so that light generated in the channel is transmitted through the optical element, the glass members being hermetically joined to enclose the continuous channel.
The invention further resides in a discharge lamp embodying a laminated, sheet, lamp envelope. It also resides in a method of making the envelope.